MONTPELIER — A political rival of Gov. Peter Shumlin has exposed what he says are troubling misfires by the technology firm being paid more than $80 million to construct the state’s new online health insurance marketplace.

Randy Brock, the Republican who lost his bid last year to unseat the Democratic governor, has written an op-ed alleging that CGI Systems and Technologies has missed all but four of the 21 “critical milestones” written into its $84 million contract.

Based on a review of contracts signed by the Shumlin administration, Brock says the state has also failed to collect millions in financial penalties owed by CGI for missing the deadlines.

Mark Larson, commissioner of the Department of Vermont Health Access, confirmed Monday that CGI has failed to meet “more than half” of the deadlines in the state’s contract with the Virginia firm, though he said he couldn’t say precisely how many had been missed or how many requirements remained unmet.

Brock says the missed deadlines are symptomatic of systemwide failings in Vermont Health Connect, the Web-based insurance portal set to launch today. And the technological shortcomings, Brock alleges, could threaten the insurance security of the more than 100,000 Vermonters who will soon be required to enroll in plans sold on the new website.

“(D)espite the multimillion dollar advertising campaign, despite the governor’s promise that everything is working fine and the system is on target, nothing could be further from the truth,” Brock writes in his op-ed. “The fact of the matter is this: The system doesn’t work.”

The accusations usher in to Vermont some of the same heated political rhetoric that has characterized the debate over the Affordable Care Act on Capitol Hill. After remaining mostly silent publicly since his 20-point loss to Shumlin in November, Brock, in his op-ed published Sunday on the nonprofit news site VTDigger.org, has stoked the embers of a health care debate that figured heavily in the race for governor last year.

Vermonters for Health Care Freedom, an organization run by Brock’s former campaign manager, Darcie Johnston, that has been critical of Shumlin’s approach to the health care exchange, is featuring Brock’s claims in a media campaign launched Monday. The campaign will include social media outreach as well as automated phone calls to “thousands” of Vermonters warning them they “could be left uninsured in just three months” and asking them to call the governor’s office to ask him to delay implementation of the exchange mandate, according to Johnston.

Individuals as well as businesses that employ 50 or fewer will be required beginning in January to get their insurance through Vermont Health Connect.

The Vermont Democratic Party, meanwhile, hit back on behalf of the Shumlin administration with a news release Monday afternoon.

“Brock and the national Republicans may be able to scare some people for a short time, but continuing his failed campaign rhetoric falls flat,” said Ryan Emerson, communications director for the Vermont Democratic Party, in response to the op-ed. “Vermonters want progress, not tea party obstructionism.”

Larson said the state believes CGI is liable for more than $5 million in penalties — the maximum sanction under the terms of the contract. Though he hasn’t yet sought to retrieve the money, Larson said he “fully expects” to collect damages from CGI but that the state’s priority right now is getting the exchange up and running.

“The milestones were set up to be measures of work along the way, but the ultimate test is, do we get the work done, so Vermonters can access this new market of health insurance options,” Larson said. “Our priority is making sure that the work gets done and that Vermonters can begin on Oct. 1 using Vermont Health Connect.”

Larson, however, said problems with the contractor notwithstanding, Vermont Health Connect is on course for a successful launch and that prospective customers will enjoy seamless coverage as they transition from the conventional insurance market to one created as a result of the Affordable Care Act.

News of the missed deadlines, and the uncollected penalties associated with them, was first reported publicly by VTDigger.org on Friday evening. The website reported the information before it published Brock’s op-ed but after it received a version of his 2,200-word commentary Friday morning.

Brock says he has no doubt that prospective users of Vermont Health Connect will find an impressive-looking website when it launches. But he says the system amounts to “smoke and mirrors” and lacks the capacity to transmit consumers’ enrollment information to either the federal data hub or to the private carriers that will be selling the actual policies on Vermont Health Connect.

Kevin Goddard, vice president of Blue Cross Blue Shield Vermont, raised concerns about connectivity earlier this month, when he said the state had yet to demonstrate its ability to transmit enrollment data to carriers in advance of the Jan. 1 date on which policies will take effect.

Larson said Vermont Health Connect has since connected with the federal data hub. While Larson said the state has yet to fully connect to the systems run by Blue Cross, MVP and Delta Dental — the only three carriers offering products in the exchange — he said those connections will be in place in time to avoid any disruption in coverage.